1. Field of the Invention
The present invention generally relates to insulators and, more particularly, is concerned with an insulator end fitting with a non-machined annular attachment flange.
2. Description of the Prior Art
Insulators are widely used by the electric utility industry for a variety of applications. Heretofore, Ohio Brass, a subsidiary of Hubbell Incorporated, has manufactured and marketed a number of different types of insulators, sometimes referred to as polymer insulators, for different applications, such as deadend, suspension, transmission, line post and the like.
Referring to FIGS. 1 to 12, there is illustrated a typical prior art insulator 10. The insulator 10 basically includes an elongated fiberglass rod 12, a plurality of weathersheds 14 disposed end-to-end along the rod 12 and an end fitting 16 attached on each of a pair of opposite ends 12A of the fiberglass rod 12. The weathersheds 14 are typically made of rubber and are either molded directly around the rod 12 or slipped thereover with the use of a dielectric grease as a rubber-rod interface. The end fittings 16 are typically of various shapes, as seen in FIGS. 2 to 6, to serve a variety of utility applications and are normally made of ductile iron and fabricated by casting and either potted (glued) or crimped onto the ends of the fiberglass rod. Whether potted or crimped to the fiberglass rod, a hole 18 is first bored in one end 16A of a solid cast body of the end fitting 16 to receive one of the ends 12A of the rod 12.
Where a crimp attachment is to be used the end fitting fabrication steps typically employed are as follows. First, a cast of the solid body of the end fitting is made, such as in a sand cast mold. Next, a first machining operation is performed on the end fitting to provide a precise known outside diameter on the one end of the end fitting to use later in boring the hole. Following next, the whole end fitting is hot dip galvanized. Then, a second machining operation is performed on the end fitting by boring the hole in the end thereof to accept the end of the fiberglass rod. By employment of the two machining operations, the flange portion left on the end fitting about the hole has the desired thickness appropriate for the crimping operation. Ductile iron is usually used for the cast portion of the end fittings and, if ductile iron is used, then low carbon steel is used for the annular attachment flange. However, cast aluminum could be used for an end fitting and then the annular attachment flange would also be aluminum.
The above-described fabrication steps, though effective in producing an end fitting having a suitable end flange portion adapted to receive an end of the fiberglass rod, are nonetheless costly and time-consuming to carry out Consequently, there is a need for innovation in the method of fabricating the end fitting that will overcome these problems without introducing new problems in place thereof.